Lithium-ion battery

ABSTRACT

A battery includes a positive electrode including a current collector and a first active material and a negative electrode including a current collector, a second active material, and a third active material. The first active material, second active material, and third active material are configured to allow doping and undoping of lithium ions. The third active material exhibits charging and discharging capacity below a corrosion potential of the current collector of the negative electrode and above a decomposition potential of the first active material.

BACKGROUND

The present invention relates generally to the field of lithiumbatteries. Specifically, the present invention relates to lithium-ionbatteries that are relatively tolerant to over-discharge conditions.

Lithium-ion batteries include a positive current collector (e.g.,aluminum such as an aluminum foil) having an active material providedthereon (e.g., LiCoO₂) and a negative current collector (e.g., coppersuch as a copper foil) having an active material (e.g., a carbonaceousmaterial such as graphite) provided thereon. Together the positivecurrent collector and the active material provided thereon are referredto as a positive electrode, while the negative current collector and theactive material provided thereon are referred to as a negativeelectrode.

FIG. 1 shows a schematic representation of a portion of a lithium-ionbattery 10 such as that described above. The battery 10 includes apositive electrode 20 that includes a positive current collector 22 anda positive active material 24, a negative electrode 30 that includes anegative current collector 32 and a negative active material 34, anelectrolyte material 40, and a separator (e.g., a polymeric microporousseparator, not shown) provided intermediate or between the positiveelectrode 20 and the negative electrode 30. The electrodes 20, 30 may beprovided as relatively flat or planar plates or may be wrapped or woundin a spiral or other configuration (e.g., an oval configuration). Theelectrode may also be provided in a folded configuration.

During charging and discharging of the battery 10, lithium ions movebetween the positive electrode 20 and the negative electrode 30. Forexample, when the battery 10 is discharged, lithium ions flow from thenegative electrode 30 to the to the positive electrode 20. In contrast,when the battery 10 is charged, lithium ions flow from the positiveelectrode 20 to the negative electrode 30.

FIG. 2 is a graph 100 illustrating the theoretical charging anddischarging behavior for a conventional lithium-ion battery. Curve 110represents the electrode potential versus a lithium reference electrodefor a positive electrode that includes an aluminum current collectorhaving a LiCoO₂ active material provided thereon, while curve 120represents the electrode potential versus a lithium reference electrodefor a negative electrode that includes a copper current collector havinga carbonaceous active material provided thereon. The difference betweencurves 110 and 120 is representative of the overall cell voltage.

As shown in FIG. 2, upon initial charging to full capacity, thepotential of the positive electrode, as shown by curve 110, increasesfrom approximately 3.0 volts to a point above the corrosion potential ofcopper used to form the negative electrode (designated by dashed line122). The potential of the negative electrode decreases fromapproximately 3.0 volts to a point below the decomposition potential ofthe LiCoO₂ active material provided on the aluminum current collector(designated by dashed line 112). Upon initial charging, the batteryexperiences an irreversible loss of capacity due to the formation of apassive layer on the negative current collector, which may be referredto as a solid-electrolyte interface (“SEI”). The irreversible loss ofcapacity is shown as a ledge or shelf 124 in curve 120.

One difficulty with conventional lithium-ion batteries is that when sucha battery is discharged to a point near zero volts, it may exhibit aloss of deliverable capacity and corrosion of the negative electrodecurrent collector (copper) and possibly of the battery case, dependingon the material used and the polarity of the case. As shown in FIG. 2,after initial charging of the battery, a subsequent discharge of thebattery in which the voltage of the battery approaches zero volts (i.e.,zero percent capacity) results in a negative electrode potential thatfollows a path designated by dashed line 126. As shown in FIG. 2, thenegative electrode potential levels off or plateaus at the coppercorrosion potential of the negative current collector (approximately 3.5volts for copper and designated by dashed line 122 in FIG. 2).

The point at which the curves 110 and 120 cross is sometimes referred toas the zero voltage crossing potential, and corresponds to a cellvoltage that is equal to zero (i.e., the difference between the twocurves equals zero at this point). Because of the degradation of thecopper current collector which occurs at the copper corrosion potential,the copper material used for the negative current collector corrodesbefore the cell reaches a zero voltage condition, resulting in a batterythat exhibits a dramatic loss of deliverable capacity.

While FIG. 2 shows the theoretical charging and discharging behavior ofa battery that may experience corrosion of the negative currentcollector when the battery approaches a zero voltage configuration, itshould be noted that there may also be cases in which the activematerial on the positive current collector may degrade innear-zero-voltage conditions. In such cases, the theoretical potentialof the positive electrode versus a lithium reference electrode woulddecrease to the decomposition potential of the positive active material(shown as line 112 in FIG. 2), at which point the positive activematerial would decompose, resulting in potentially decreased protectionagainst future over-discharge conditions.

Because damage to the lithium-ion battery may occur in the event of alow voltage condition, conventional lithium-ion batteries may includeprotection circuitry and/or may be utilized in devices that includeprotection circuitry which substantially reduces the current drain fromthe battery (e.g., by disconnecting the battery).

The medical device industry produces a wide variety of electronic andmechanical devices for treating patient medical conditions. Dependingupon the medical condition, medical devices can be surgically implantedor connected externally to the patient receiving treatment. Cliniciansuse medical devices alone or in combination with drug therapies andsurgery to treat patient medical conditions. For some medicalconditions, medical devices provide the best, and sometimes the only,therapy to restore an individual to a more healthful condition and afuller life.

It may be desirable to provide a source of battery power for suchmedical devices, including implantable medical devices. In such cases,it may be advantageous to provide a battery that may be recharged. Itmay also be advantageous to provide a battery that may be discharged toa near zero voltage condition without substantial risk that the batterymay be damaged (e.g., without corroding one of the electrodes or thebattery case, decomposing the positive active material, etc.) such thatthe performance of the battery is degraded in subsequent charging anddischarging operations.

It would be advantageous to provide a battery (e.g., a lithium-ionbattery) that may be discharged to near zero volts without producing asubsequent decrease in the amount of deliverable capacity or producing acorroded negative electrode or battery case. It would also beadvantageous to provide a battery that compensates for the irreversibleloss of capacity resulting from initial charging of the battery to allowthe battery to be used in near zero voltage conditions withoutsignificant degradation to battery performance. It would also beadvantageous to provide a medical device (e.g., an implantable medicaldevice) that utilizes a battery that includes any one or more of theseor other advantageous features.

SUMMARY

An exemplary embodiment relates to a battery that includes a positiveelectrode comprising a current collector and a first active material anda negative electrode comprising a current collector, a second activematerial, and a third active material. The first active material, secondactive material, and third active material are configured to allowdoping and undoping of lithium ions. The third active material exhibitscharging and discharging capacity below a corrosion potential of thecurrent collector of the negative electrode and above a decompositionpotential of the first active material.

Another exemplary embodiment relates to a lithium-ion battery thatincludes a positive current collector, and a negative current collector.An active material is provided on the positive current collector. Anactive material layer is also provided on the negative currentcollector. The active material layer comprises a primary active materialand a secondary active material, the secondary active materialexhibiting charge and discharge capacity below a corrosion potential ofthe negative current collector. The secondary active material does notinclude lithium. The lithium-ion battery also includes a mass of lithiumprovided in electrical contact with a portion of the negative currentcollector.

Another exemplary embodiment relates to a lithium-ion battery thatincludes a positive electrode comprising a positive current collectorand an active material provided on at least one side of the positivecurrent collector. The lithium-ion battery also includes a negativeelectrode having a negative current collector and a primary activematerial and an auxiliary active material provided on at least one sideof the negative current collector. The auxiliary active materialcomprises lithium and provides charging and discharging capacity for thepositive electrode below a corrosion potential of the negative currentcollector and above a decomposition potential of the active materialprovided on the positive current collector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a conventional lithium-ionbattery.

FIG. 2 is a graph illustrating the theoretical charging and dischargingbehavior for a conventional lithium-ion battery such as that shownschematically in FIG. 1.

FIG. 3 is a schematic cross-sectional view of a portion of a lithium-ionbattery according to an exemplary embodiment.

FIG. 4 is a schematic cross-sectional view of a portion of a lithium-ionbattery according to another exemplary embodiment.

FIG. 5 is a graph illustrating the theoretical charging and dischargingbehavior for a lithium-ion battery such as that shown in FIG. 3.

FIG. 6 is a schematic view of a system in the form of an implantablemedical device implanted within a body or torso of a patient.

FIG. 7 is schematic view of another system in the form of an implantablemedical device.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

With reference to FIG. 3, a schematic cross-sectional view of a portionof a lithium-ion battery 200 is shown according to an exemplaryembodiment. According to an exemplary embodiment, the battery 200 has arating of between approximately 10 and 1000 milliampere hours (mAh).According to another exemplary embodiment, the battery has a rating ofbetween approximately 100 and 400 mAh. According to another exemplaryembodiment, the battery is an approximately 300 mAh battery. Accordingto another exemplary embodiment, the battery is an approximately 75 mAhbattery.

The battery 200 includes at least one positive electrode 210 and atleast one negative electrode 220. The electrodes may be provided as flator planar components of the battery 200, may be wound in a spiral orother configuration, or may be provided in a folded configuration. Forexample, the electrodes may be wrapped around a relatively rectangularmandrel such that they form an oval wound coil for insertion into arelatively prismatic battery case. According to other exemplaryembodiments, the battery may be provided as a button cell battery, athin film solid state battery, or as another lithium-ion batteryconfiguration.

The battery case (not shown) may be made of stainless steel or anothermetal. According to an exemplary embodiment, the battery case may bemade of titanium, aluminum, or alloys thereof. According to anotherexemplary embodiment, the battery case may be made of a plastic materialor a plastic-foil laminate material (e.g., an aluminum foil providedintermediate a polyolefin layer and a polyester layer).

According to an exemplary embodiment, the negative electrode is coupledto a stainless steel case by a member or tab comprising nickel or anickel alloy. An aluminum or aluminum alloy member or tab may be coupledor attached to the positive electrode. The nickel and aluminum tabs mayserve as terminals for the battery according to an exemplary embodiment.

The dimensions of the battery 200 may differ according to a variety ofexemplary embodiments. For example, according to one exemplaryembodiment in which the electrodes are wound such that they may beprovided in a relatively prismatic battery case, the battery hasdimensions of between approximately 30-40 mm by between approximately20-30 mm by between approximately 5-7 mm. According to another exemplaryembodiment, the dimensions of the battery are approximately 20 mm by 20mm by 3 mm. According to another exemplary embodiment, a battery may beprovided in the form of a button cell type battery having a diameter ofapproximately 30 mm and a thickness of approximately 3 mm. It will beappreciated by those of skill in the art that such dimensions andconfigurations as are described herein are illustrative only, and thatbatteries in a wide variety of sizes, shapes, and configurations may beproduced in accordance with the novel concepts described herein.

An electrolyte 230 is provided intermediate or between the positive andnegative electrodes to provide a medium through which lithium ions maytravel. According to an exemplary embodiment, the electrolyte may be aliquid (e.g., a lithium salt dissolved in one or more non-aqueoussolvents). According to another exemplary embodiment, the electrolytemay be a lithium salt dissolved in a polymeric material such aspoly(ethylene oxide) or silicone. According to another exemplaryembodiment, the electrolyte may be an ionic liquid such asN-methyl-N-alkylpyrrolidinium bis(trifluoromethanesulfonyl)imide salts.According to another exemplary embodiment, the electrolyte may be asolid state electrolyte such as a lithium-ion conducting glass such aslithium phosphorous oxynitride (LiPON).

Various other electrolytes may be used according to other exemplaryembodiments. For example, according to an exemplary embodiment, theelectrolyte may be a 1:1 mixture of ethylene carbonate to diethylenecarbonate (EC:DEC) in a 1.0 M salt of LiPF₆. According to anotherexemplary embodiment, the electrolyte may include a polypropylenecarbonate solvent and a lithium bis-oxalatoborate salt (sometimesreferred to as LiBOB). According to other exemplary embodiments, theelectrolyte may comprise one or more of a PVDF copolymer, aPVDF-polyimide material, and organosilicon polymer, a thermalpolymerization gel, a radiation cured acrylate, a particulate withpolymer gel, an inorganic gel polymer electrolyte, an inorganicgel-polymer electrolyte, a PVDF gel, polyethylene oxide (PEO), a glassceramic electrolyte, phosphate glasses, lithium conducting glasses,lithium conducting ceramics, and an inorganic ionic liquid or gel, amongothers.

A separator 250 is provided intermediate or between the positiveelectrode 210 and the negative electrode 220. According to an exemplaryembodiment, the separator 250 is a polymeric material such as apolypropylene/polyethelene or another polyolefin multilayer laminatethat includes micropores formed therein to allow electrolyte and lithiumions to flow from one side of the separator to the other. The thicknessof the separator 250 is between approximately 10 micrometers (μm) and 50μm according to an exemplary embodiment. According to a particularexemplary embodiment, the thickness of the separator is approximately 25μm and the average pore size of the separator is between approximately0.02 μm and 0.1 μm.

The positive electrode 210 includes a current collector 212 made of aconductive material such as a metal. According to an exemplaryembodiment, the current collector 212 comprises aluminum or an aluminumalloy. According to an exemplary embodiment, the thickness of thecurrent collector 212 is between approximately 5 μm and 75 μm. Accordingto a particular exemplary embodiment, the thickness of the currentcollector 212 is approximately 20 μm. It should also be noted that whilethe positive current collector 212 has been illustrated and described asbeing a thin foil material, the positive current collector may have anyof a variety of other configurations according to various exemplaryembodiments. For example, the positive current collector may be a gridsuch as a mesh grid, an expanded metal grid, a photochemically etchedgrid, or the like.

The current collector 212 has a layer of active material 214 providedthereon (e.g., coated on the current collector). While FIG. 3 shows thatthe active material 214 is provided on only one side of the currentcollector 212, it should be understood that a layer of active materialsimilar or identical to that shown as active material 214 may beprovided or coated on both sides of the current collector 212.

According to an exemplary embodiment, the active material 214 is amaterial or compound that includes lithium. The lithium included in theactive material 214 may be doped and undoped during discharging andcharging of the battery, respectively. According to an exemplaryembodiment, the active material 214 is lithium cobalt oxide (LiCoO₂).According to another exemplary embodiment, the positive active materialis of the form LiCo_(x)Ni_((1-x))O₂, with x being between approximately0.05 and 0.8. According to another exemplary embodiment, the primaryactive material is of the form LiAl_(x)Co_(y)Ni_((1-x-y))O₂, where x isbetween approximately 0.05 and 0.3 and y is between approximately 0.1and 0.3. According to other exemplary embodiments, the primary activematerial may include LiMn₂O₄.

According to various other exemplary embodiments, the active materialprovided on the current collector 212 may include a material such as amaterial of the form Li_(1-x)MO₂ where M is a metal (e.g., LiCoO₂,LiNiO₂, and LiMnO₂), a material of the form Li_(1-w)(M′_(x)M″_(y))O₂where M′ and M″ are different metals (e.g., Li(Ni_(x)Mn_(y))O₂,Li(Ni_(1/2)Mn_(1/2))O₂, Li(Cr_(x)Mn_(1-x))O₂, Li(Al_(x)Mn_(1-x))O₂,Li(Co_(x)M_(1-x))O₂, Li(Co_(x)Ni_(1-x))O₂, and Li(Co_(x)Fe_(1-x))O₂), amaterial of the form Li_(1-w)(Mn_(x)Ni_(y)Co_(z))O₂ (e.g.,LiCo_(x)Mn_(y)Ni_((1-x-y))O₂, Li(Mn_(1/3)Ni_(1/3)Co_(1/3))O₂,Li(Mn_(1/3)Ni_(1/3)Co_(1/3-x)Mg_(x))O₂, Li(Mn_(0.4)Ni_(0.4)CO_(0.2))O₂,and Li(Mn_(0.1)Ni_(0.1)Co_(0.8))O₂), a material of the formLi_(1-w)(Mn_(x)Ni_(x)Co_(1-2x))O₂, a material of the formLi_(1-w)(Mn_(x)Ni_(y)Co_(z)Al_(w))O₂, a material of the formLi_(1-w)(Ni_(x)Co_(Y)Al_(z))O₂ (e.g., Li(Ni_(0.8)Co_(0.15)Al_(0.05))O₂),a material of the form Li_(1-w)(Ni_(x)Co_(Y)M_(z))O₂, where M is ametal, a material of the form Li_(1-w)(Ni_(x)Mn_(y)M_(z))O₂, where M isa metal, a material of the form Li(Ni_(x-y)Mn_(y)Cr_(2-x))O₄. LiMn₂O₄, amaterial of the form LiM′M″₂O₄ where M′ and M″ are different metals(e.g., LiMn_(2-y-z)Ni_(y), Li_(z)O₄, LiMn_(1.5)Ni_(0.5)O₄, LiNiCuO₄,LiMn_(1-x)Al_(x)O₄, LiNi_(0.5)Ti_(0.5)O₄, andLi_(1.05)Al_(0.1)Mn_(1.85)O_(4-z)F_(z)) Li₂MnO₃, a material of the formLi_(x)V_(y)O_(z) (e.g., LiV₃O₈, LiV₂O₅, and LiV₆O₁₃), a material of theform LiMPO₄ where M is a metal or LiM_(x)′M″_(1-x)PO₄ where M′ and M″are different metals (e.g., LiFePO₄, LiFe_(x)M_(1-x)PO₄, LiVOPO₄, andLi₃V₂(PO₄)₃), and LIMPO_(4x) where M is a metal such as iron or vanadiumand x is a halogen such as fluorine, and combinations thereof.

A binder material may also be utilized in conjunction with the activematerial 214. For example, according to an exemplary embodiment, theactive material may include a conductive additive such as carbon blackand a binder such as polyvinylidine fluoride (PVDF) or an elastomericpolymer.

According to an exemplary embodiment, the thickness of the activematerial 214 is between approximately 0.1 μm and 3 mm. According to aparticular exemplary embodiment, the thickness of the active material214 is between approximately 25 μm and 300 μm. According to a particularexemplary embodiment, the thickness of the layer of active material 214is approximately 75 μm.

The negative electrode 220 includes a current collector 222 that is madeof a conductive material such as a metal. According to an exemplaryembodiment, the current collector 222 is copper or a copper alloy.According to another exemplary embodiment, the current collector 222 maybe titanium or a titanium alloy. According to another exemplaryembodiment, the current collector 222 is nickel or a nickel alloy.According to another exemplary embodiment in which the negative activematerial 224 is not carbon, the current collector 222 is aluminum or analuminum alloy. It should also be noted that while the negative currentcollector 222 has been illustrated and described as being a thin foilmaterial, the positive current collector may have any of a variety ofother configurations according to various exemplary embodiments. Forexample, the positive current collector may be a grid such as a meshgrid, an expanded metal grid, a photochemically etched grid, or thelike.

According to an exemplary embodiment, the thickness of the currentcollector 222 is between approximately 100 nm and 100 μm. According to aparticular exemplary embodiment, the thickness of the current collector222 is between approximately 5 μm and 25 μm. According to a particularexemplary embodiment, the thickness of the current collector isapproximately 10 μm.

The negative current collector 222 has a layer of active material 224provided thereon. While FIG. 3 shows that the active material 224 isprovided on only one side of the current collector 222, it should beunderstood that a layer of active material similar or identical to thatshown may be provided or coated on both sides of the current collector222.

Layer 224 includes a primary active material 226 and a secondary orauxiliary active material 228. While the primary active material 226 andthe secondary active material 228 are shown as being provided as asingle layer of material in FIG. 3, it will be appreciated that theprimary active material 226 and the secondary active material 228 may beprovided as separate individual layers (see, e.g., FIG. 4). A bindermaterial and/or a solvent (not shown) may also be utilized inconjunction with the active material 224. For example, according to anexemplary embodiment, the active material may include a conductiveadditive such as carbon black and a binder such as polyvinylidinefluoride (PVDF) or an elastomeric polymer.

According to exemplary embodiment, the primary active material 226 is acarbonaceous material (e.g., carbon such as graphite). According toanother exemplary embodiment, the primary active material 226 is alithium titanate material such as Li₄Ti₅O₁₂. One advantage of using alithium titanate material in place of a carbonaceous material is that itis believed that the use of a lithium titanate material allows forcharging and discharging of the battery at higher rates than is capableusing carbonaceous materials.

Other lithium titanate materials which may be suitable for use as thenegative active material may include one or more of include thefollowing lithium titanate spinel materials: H_(x)Li_(y-x)TiO_(x)O₄,H_(x)Li_(y-x)TiO_(x)O₄, Li₄M_(x)Ti_(5-x)O₁₂, Li_(x)Ti_(y)O₄,Li_(x)Ti_(y)O₄, Li₄[Ti_(1.67)Li_(0.33-y)M_(y)]O₄, Li₂TiO₃,Li₄Ti_(4.75)V_(0.25)O₁₂, Li₄Ti_(4.75)Fe_(0.25)O_(11.88), andLi₄Ti_(4.5)Mn_(0.5)O₁₂, and LiM′M″XO₄ (where M′ is a metal such asnickel, cobalt, iron, manganese, vanadium, copper, chromium, molybdenum,niobium, or combinations thereof), M″ is an optional three valentnon-transition metal, and X is zirconium, titanium, or a combination ofthese two. Note that such lithium titanate spinel materials may be usedin any state of lithiation (e.g., Li_(4+x)Ti₅O₁₂, where 0≦x≦3).

One advantage of using a lithium titanate material instead of acarbonaceous material is that it is believed that the use of a lithiumtitanate material allows for charging and discharging of the battery athigher rates than is capable using carbonaceous materials. According toother exemplary embodiments, the negative active material 224 may becarbon, Li_(x)Al, Li_(x)Sn, Li_(x)Si, Li_(x)SnO, metal nanoparticlecomposites (e.g., including Li_(x)Al, Li_(x)Sn, Li_(x)Si, or Li_(x)SnO),or carbon-coated lithium titanate. Lithium titanate materials are alsobelieved to offer superior cycle life because they are so called“zero-strain” materials. Zero strain materials have crystal latticeswhich do not experience shrinkage or contraction with lithiumdoping/de-doping, making them free from strain-related degradationmechanisms.

Another advantageous feature of using a lithium titanate material isthat it is believed that when used in a negative electrode of alithium-ion battery, such materials will cycle lithium at a potentialplateau of about 1.5 V versus a lithium reference electrode. This issubstantially higher than graphitic carbon, which is traditionally usedin lithium ion batteries, and cycles lithium down to about 0.1 V in thefully charged state. As a result, the battery using lithium titanate isbelieved to be less likely to result in plating of lithium (which occursat 0 V versus a lithium reference) while being charged. Lithium platingis a well-known phenomenon that can lead to loss in performance oflithium ion batteries. Being free from the risk lithium plating, cellswith lithium titanate negative electrodes may also be charged at ratesthat exceed those with carbon negative electrodes. For example, a commonupper limit for the rate of charge in lithium ion batteries is about 1C(meaning that the battery can be fully charged from the discharged statein one hour). Conversely, it has been reported in literature thatlithium titanate may be charged at rates up to 10C (i.e., attaining fullcharge in 1/10 hour, or six minutes). Being able to recharge a batterymore quickly substantially increases the functionality of devices thatemploy such a battery. A further advantage of the higher potential ofthe lithium titanate material is that it avoids decomposition of organicsolvents (such as propylene carbonate) commonly used in lithium ionbatteries. In so doing, it may reduce negative consequences such asformation of gas, cell swelling, and reduction of reversible batterycapacity.

The secondary active material 228 is a material that is selected to haverelatively significant charge and discharge capacity below the corrosionpotential of the material used for a negative current collector 222provided as part of the negative electrode 220 and above thedecomposition potential of the active material 214 provided on thepositive current collector 212. The secondary active material is alsoselected to be stable over its full potential-composition range in theelectrolyte. For example, according to an exemplary embodiment in whichthe negative current collector 222 comprises copper, for which thecorrosion potential is approximately 3.5 volts, the secondary activematerial 228 includes significant charge and discharge capacity below3.5 volts.

The secondary active material 228 may or may not contain lithium.According to an exemplary embodiment in which the secondary activematerial does not include lithium, the secondary active material isV₆O₃. According to another exemplary embodiment in which the secondaryactive material includes lithium, the secondary active material isLiMn₂O₄. According to various other exemplary embodiments, the secondaryactive material may be selected from the following materials andcombinations thereof: V₂O₅, V₆O₁₃, LiMn₂O₄ (spinel), LiM_(x)Mn_((2-x))O₄(spinel) where M is metal (including Li) and x is between approximately0.05 and 0.4, Li₅Ti₄O₁₂, Li_(x)VO₂ (where x is between approximately 0and 1), V₃₀₈, MoO₃, TiS₂, WO₂, MoO₂, and RuO₂, as well as theirpartially or fully lithiated counterparts.

Any lithium included in the secondary active material 228 of thenegative electrode has significant charge/discharge capacity that liesbelow the corrosion potential of the negative current collector and/orany battery components to which it is electrically connected (e.g., thecase) and above the decomposition potential of the positive electrodeactive material. The secondary active material containselectrochemically active lithium in the as-constructed state. Thelithium becomes significantly doped at a potential below the corrosionpotential for the negative current collector 222. In so doing, thismaterial lowers the final potential of the positive electrode in thedischarge state, so that the zero voltage crossing potential remainsbelow the corrosion potential of the negative current collector and thebattery case. The secondary active material may be capable of releasingthe lithium when the battery is charged.

It should be noted that while a variety of materials have been describedabove as being useful for secondary active material 228, a variety ofadditional materials may be utilized in addition to or in place of suchmaterials. For example, the secondary active material may comprise anoxide material such as one or more of Li_(x)MoO₃ (0<x≦2), Li_(x)MoO₂(0<x≦1), Li_(x)Mo₂O₄ (0<x≦0), Li_(x)MnO₂ (0<x≦1), Li_(x)Mn₂O₄ (0<x≦2),Li_(x)V₂O₅ (0<x≦2.5), Li_(x)V₃O₈ (0<x≦3.5), Li_(x)V₆O₃ (0<x≦6 forLi_(x)VO_(2.19) and 0<x≦3.6 for Li_(x)VO_(2.17)), Li_(x)VO₂ (0<x≦1),Li_(x)WO₃ (0<x≦1), Li_(x)WO₂ (0<x≦1), Li_(x)TiO₂ (anatase) (0<x≦1),Li_(x)Ti₂O₄ (0<x≦2), Li_(x)RuO₂ (0<x≦1), Li_(x)Fe₂O₃ (0<x≦2),Li_(x)Fe₃O₄ (0<x≦2), Li_(x)Cr₂O (0<x≦3), Li_(x)Cr (0<x≦3.8),Li_(x)Ni_(y)Co_(1-y)O₂ (0<x≦1, 0.90<y≦1.00), where x is selected suchthat these materials have little or no lithium that becomes undopedbelow the corrosion potential of the negative current collector duringthe first charge of the battery.

According to another exemplary embodiment, the secondary active materialmay comprise a sulfide material such as one or more of Li_(x)V₂S₅(0<x≦4.8), Li_(x)TaS₂ (0<x≦1), Li_(x)FeS (0<x≦1), Li_(x)FeS₂ (0<x≦1),Li_(x)NbS₃ (0<x≦2.4), Li_(x)MoS₃ (0<x≦3), Li_(x)MoS₂ (0<x≦1), Li_(x)TiS₂(0<x≦1), Li_(x)ZrS₂ (0<x≦1), Li_(x)Fe_(0.25) V_(0.75)S₂ (0<x≦1),Li_(x)Cr_(0.75)V_(0.25)S₂ (0<x≦0.65), Li_(x)Cr_(0.5)V_(0.5)S₂ (0<x≦1)where x is selected such that these materials have little or no lithiumthat becomes undoped below the corrosion potential of the negativecurrent collector during the first charge of the battery.

According to another exemplary embodiment, the secondary active materialmay comprise a selenide material such as one or more of Li_(x)NbSe₃(0<x≦3). Li_(x)VSe₂ (0<x≦1). Various other materials may also be used,for example, Li_(x)NiPS₃ (0<x≦1.5) and Li_(x)FePS₃ (0<x≦1.5) where x isselected such that these materials have little or no lithium thatbecomes undoped below the corrosion potential of the negative currentcollector during the first charge of the battery.

According to an exemplary embodiment in which the secondary activematerial 228 does not include lithium in the as-constructed state (e.g.,the secondary active material is V₆O₁₃), a mechanism is provided tolithiate the secondary active material 228. According to an exemplaryembodiment, a mass or quantity of lithium (e.g., a lithium “patch”) maybe provided, as will be discussed in greater detail below.

According to various exemplary embodiments, the thickness of the activematerial 224 is between approximately 0.1 μm and 3 mm. According toother exemplary embodiments, the thickness of the layer of activematerial 224 may be between approximately 25 μm and 300 μm. According toa particular exemplary embodiment, the thickness of the active material224 is approximately 75 μm. In embodiments in which the primary activematerial 226 and the secondary active material 228 are provided asseparate layers of active material, the thickness of the primary activematerial 226 is between approximately 25 μm and 300 μm (andapproximately 75 μm according to a particular exemplary embodiment),while the thickness of the secondary active material 218 is betweenapproximately 5 μm and 60 μm (and approximately 10 μm according to aparticular exemplary embodiment).

As shown in FIG. 3, a mass or quantity of electrochemically activelithium (shown as a piece of lithium in the form of a lithium patch ormember 240) is shown as being coupled or attached to the negativecurrent collector 222. Such a configuration corresponds to a situationin which the secondary active material 228 is provided without includingelectrochemically active lithium (e.g., the secondary active material228 does not include lithium as it is coated on the negative currentcollector). One such exemplary embodiment involves the use of V₆O₁₃ forthe secondary active material. In contrast, FIG. 4 shows a configurationin which the secondary active material 228 is provided as a lithiatedmaterial (e.g., LiMn₂O₄). In such an embodiment, a lithium patch is notnecessary.

The electrochemically active lithium may be provided in other locationsin the negative electrode 220 and/or may have a different size or shapethan that shown schematically in FIG. 3. For example, theelectrochemically active lithium may be provided as a disc or as arectangular piece of material coupled to the negative current collector.While the electrochemically active lithium is shown as being provided ona single side of the current collector 222 in FIG. 3 (e.g., as a lithiumpatch), separate lithium patches may be provided on opposite sides ofthe current collector 222. Further, multiple lithium patches may beprovided on one or more of the sides of the current collector 222. Inanother example, the lithium may be provided elsewhere within thebattery and connected (e.g., by a wire) to the current collector 222.

The electrochemically active lithium may be added through a chemical orelectrochemical process. Such processes could include the addition ofbutyl lithium or electrical contact with metallic lithium or any otherlithium source containing lithium and having an electrochemicalpotential lower than that of the secondary material (and optionallyadding an electrolyte to activate the process). According to anotherexemplary embodiment, the process may be an electrolytic process, inwhich the precursor secondary material is polarized to a cathodicpotential at which lithium ions present in an electrolyte are insertedinto the precursor material. It should also be noted thatelectrochemically cyclable lithium may be added by addinglithium-containing compounds such as a lithium intermetallic compoundsuch as a lithium-aluminum compound, a lithium-tin compound, alithium-silicon compound, or any other similar compound thatirreversibly donates lithium at a potential below that of the corrosionpotential of the negative current collector (and any material to whichit is electrically connected).

According to another exemplary embodiment, the electrochemically activeor cyclable lithium may be added as finely divided or powdered lithium.Such powdered lithium may include a passive coating (e.g., a thin layeror film of lithium carbonate) provided thereon to reduce the reactivityof the powdered lithium with air and moisture. Such material may bemixed with the negative electrode active material prior to applicationof the negative electrode active material to fabrication of the cells ormay be added as another separate active material layer. According to anexemplary embodiment, the finely divided or powdered lithium particleshave a diameter of between approximately 1 μm and 100 μm, and accordingto a particular embodiment, between approximately 5 μm and 30 μm.

One advantage of providing electrochemically active lithium at thenegative electrode (e.g., in the form of one or more lithium patches) isthat the secondary active material 228 may be partially or completelylithiated by the lithium to compensate for the irreversible loss ofcapacity which occurs upon the first charging of the battery 200. Forexample, when the battery cell is filled with electrolyte, lithium fromthe lithium patch 240 is oxidized and inserted into the negative activematerial (i.e., the lithium in the electrochemically active lithium iseffectively “shorted” to the negative active material).

The electrochemically active lithium may also provide a number ofadditional advantages. For example, it may act to maintain the potentialof the negative current collector below its corrosion potential prior toinitial charging (“formation”) of the battery. The electrochemicallyactive lithium may also aid in the formation of the solid-electrolyteinterface (“SEI”) at the negative electrode. Further, theelectrochemically active lithium may provide the “formation” of theactive material on the negative electrode without a correspondingreduction in battery capacity as would occur when the source of lithiumfor formation is the active material from the positive electrode.

The amount of electrochemically active lithium is selected such theamount of electrochemical equivalents provided by the electrochemicallyactive lithium at minimum corresponds to the irreversible capacity ofthe negative electrode active material and at maximum corresponds to thesum of the irreversible capacity of the negative electrode activematerial and the capacity of the secondary active material 228. In thismanner, the electrochemically active lithium at least compensates forthe irreversible loss of capacity which occurs on initial charging ofthe battery 200 and most preferably corresponds to the sum of theirreversible capacity of the negative electrode active material and thecapacity of the secondary active material 228.

According to an exemplary embodiment in which a lithium patch 240 isutilized, the size of the lithium patch 240 is between approximately 1.4cm×1.4 cm×0.11 cm, which corresponds to approximately 0.013 grams (e.g.,approximately 50 mAh). The specific size of the lithium patch may varyaccording to other exemplary embodiments (e.g., approximately 5-25percent of the capacity of either the negative or positive electrode).

FIG. 5 is a graph 300 illustrating the theoretical charging anddischarging behavior for a lithium-ion battery constructed in accordancewith an exemplary embodiment such as that shown and described withregard to FIG. 3. Curve 310 represents the electrode potential versus alithium reference electrode for a positive electrode (e.g., positiveelectrode 210) that includes an aluminum current collector having aLiCoO₂ primary active material provided thereon.

Curve 320 represents the electrode potential versus a lithium referenceelectrode for a negative electrode that includes a copper currentcollector having a primary active material (i.e., a carbonaceousmaterial such as carbon), a non-lithiated secondary active material, anda lithium patch provided thereon. The difference between curves 310 and320 is representative of the overall cell voltage of the battery.

The secondary active material is selected to provide significantcharging/discharging capacity below the corrosion potential (shown asdashed line 322) of the negative current collector and above thedecomposition potential (shown as dashed line 312) of the LiCoO₂positive electrode active material, in addition to its ability to remainstable over its full potential-composition range in the electrolyte.According to an exemplary embodiment, the secondary active material isV₆O₁₃. According to various other exemplary embodiments, the secondaryactive material may be selected from the following materials andcombinations thereof: V₂O₅, V₆O₁₃, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, andRuO₂.

It should be noted that the theoretical charging and discharge behaviorfor the negative electrode is believed to be qualitatively similar tothat shown in FIG. 5 for a copper current collector having a Li₄Ti₅O₁₂primary active material provided thereon (as opposed to a carbon activematerial), with the relatively flat portion of the curve 320 beingshifted upward to a level of approximately 1.57 volts (in contrast tothe approximately 0.1 volts for the carbon active material).

As shown in FIG. 5, upon initial charging to full capacity, thepotential of the positive electrode, as shown by curve 310, increasesfrom approximately 3.0 volts (shown as point 311) to a point above thecorrosion potential of copper used to form the negative currentcollector (designated by dashed line 322). When the battery issubsequently discharged toward a zero voltage condition, the positiveelectrode potential will continue along a portion 314 of curve 310 to apoint below approximately 3.0 volts (as shown by the dashed portion ofcurve 310 in FIG. 5).

The potential of the negative electrode decreases from approximately 3.0volts on initial charging to a point below the decomposition potentialof the LiCoO₂ active material provided on the positive current collector(designated by dashed line 312). According to an exemplary embodiment,the corrosion potential of copper is approximately 3.5 volts, while thedecomposition potential of the LiCoO₂ active material provided on thepositive current collector is approximately 1.6 volts. According toanother exemplary embodiment, the decomposition potential of the LiCoO₂active material is approximately 1.35 volts.

The initial capacity of the negative electrode is provided by thesecondary active material (e.g., V₆O₃), as illustrated by the portion ofthe graph 300 designated by arrow 328. After the capacity of thesecondary active material is exhausted, the battery experiences anirreversible loss of capacity due to the formation of a passive layer onthe negative electrode, which may be referred to as a solid-electrolyteinterface (“SEI”). The irreversible loss of capacity is shown as a ledgeor shelf 324 in curve 320. The lithium patch is provided so as tocompensate for the irreversible loss of capacity, and may be providedsuch that it compensates both for the initial capacity of the secondaryactive material (e.g., arrow 328) and the irreversible loss of capacity(ledge 324).

Upon discharging the battery to a point approaching zero volts, thenegative electrode potential follows a path designated by a dashedportion 326 of the curve 320. However, because the secondary activematerial is chosen to have significant charging/discharging capacitybelow the corrosion potential of the negative current collector andabove the decomposition potential of the LiCoO₂ primary active material,the zero voltage crossing potential (shown as point 330) is below thecorrosion potential of the negative current collector and above thedecomposition potential of the LiCoO₂ primary active material, thusavoiding corrosion of the negative current collector (and potentially ofthe battery case or any other battery component in electrical contact orcommunication with the negative electrode) and any associated loss ofbattery charging capacity. One advantageous feature of such anarrangement is that the battery may be repeatedly cycled (i.e., chargedand discharged) to near-zero-voltage conditions without significantdecline in battery performance.

It is intended that a lithium-ion battery such as that described hereinmay be fully discharged while the materials for both electrodes,including their corresponding current collectors, are stable (e.g.,corrosion of the current collectors and/or the decomposition of activematerial may be avoided, etc.). One potential advantageous feature ofsuch an arrangement is that the occurrence of reduced devicefunctionality (i.e., the need to recharge more frequently) and corrosionof the current collectors and battery case (with the incumbentpossibility of leaking potentially corrosive and toxic battery contents)may be reduced or avoided.

Various advantageous features may be obtained by utilizing batteriessuch as those shown and described herein. For example, use of suchbatteries may eliminate the need to utilize circuitry to disconnectbatteries approaching near-zero voltage conditions. By not utilizingcircuitry for this function, volume and cost reductions may be obtained.

According to an exemplary embodiment, lithium-ion batteries such asthose described above may be used in conjunction with medical devicessuch as medical devices that may be implanted in the human body(referred to as “implantable medical devices” or “IMD's”).

FIG. 6 illustrates a schematic view of a system 400 (e.g., animplantable medical device) implanted within a body or torso 432 of apatient 430. The system 400 includes a device 410 in the form of animplantable medical device that for purposes of illustration is shown asa defibrillator configured to provide a therapeutic high voltage (e.g.,700 volt) treatment for the patient 430.

The device 410 includes a container or housing 414 that is hermeticallysealed and biologically inert according to an exemplary embodiment. Thecontainer may be made of a conductive material. One or more leads 416electrically connect the device 410 and to the patient's heart 420 via avein 422. Electrodes 417 are provided to sense cardiac activity and/orprovide an electrical potential to the heart 420. At least a portion ofthe leads 416 (e.g., an end portion of the leads shown as exposedelectrodes 417) may be provided adjacent or in contact with one or moreof a ventricle and an atrium of the heart 420.

The device 410 includes a battery 440 provided therein to provide powerfor the device 410. According to another exemplary embodiment, thebattery 440 may be provided external to the device or external to thepatient 430 (e.g., to allow for removal and replacement and/or chargingof the battery). The size and capacity of the battery 440 may be chosenbased on a number of factors, including the amount of charge requiredfor a given patient's physical or medical characteristics, the size orconfiguration of the device, and any of a variety of other factors.According to an exemplary embodiment, the battery is a 500 mAh battery.According to another exemplary embodiment, the battery is a 300 mAhbattery. According to various other exemplary embodiments, the batterymay have a capacity of between approximately 10 and 1000 mAh.

According to other exemplary embodiments, more than one battery may beprovided to power the device 410. In such exemplary embodiments, thebatteries may have the same capacity or one or more of the batteries mayhave a higher or lower capacity than the other battery or batteries. Forexample, according to an exemplary embodiment, one of the batteries mayhave a capacity of approximately 500 mAh while another of the batteriesmay have a capacity of approximately 75 mAh.

One or more capacitors (shown as capacitor bank 450) are provided in thedevice to store energy provided by the battery 440. For example, thesystem 410 may be configured such that when the device 410 determinesthat a therapeutic high-voltage treatment is required to establish anormal sinus rhythm for the heart 420, the capacitors in the capacitorbank 450 are charged to a predetermined charge level by the battery 440.Charge stored in the capacitors may then be discharged via the leads 416to the heart 420. According to another exemplary embodiment, thecapacitors may be charged prior to determination that a stimulatingcharge is required by the heart such that the capacitors may bedischarged as needed.

According to another exemplary embodiment shown in FIG. 7, animplantable neurological stimulation device 500 (an implantable neurostimulator or INS) may include a battery 502 such as those describedabove with respect to the various exemplary embodiments. Examples ofother neuro stimulation products and related components are shown anddescribed in a brochure titled “Implantable Neurostimulation Systems”available from Medtronic, Inc.

An INS generates one or more electrical stimulation signals that areused to influence the human nervous system or organs. Electricalcontacts carried on the distal end of a lead are placed at the desiredstimulation site such as the spine or brain and the proximal end of thelead is connected to the INS. The INS is then surgically implanted intoan individual such as into a subcutaneous pocket in the abdomen,pectoral region, or upper buttocks area. A clinician programs the INSwith a therapy using a programmer. The therapy configures parameters ofthe stimulation signal for the specific patient's therapy. An INS can beused to treat conditions such as pain, incontinence, movement disorderssuch as epilepsy and Parkinson's disease, and sleep apnea. Additionaltherapies appear promising to treat a variety of physiological,psychological, and emotional conditions. Before an INS is implanted todeliver a therapy, an external screener that replicates some or all ofthe INS functions is typically connected to the patient to evaluate theefficacy of the proposed therapy.

The INS 500 includes a lead extension 522 and a stimulation lead 524.The stimulation lead 524 is one or more insulated electrical conductorswith a connector 532 on the proximal end and electrical contacts (notshown) on the distal end. Some stimulation leads are designed to beinserted into a patient percutaneously, such as the Model 3487APisces-Quad® lead available from Medtronic, Inc. of Minneapolis Minn.,and stimulation some leads are designed to be surgically implanted, suchas the Model 3998 Specify® lead also available from Medtronic.

Although the lead connector 532 can be connected directly to the INS 500(e.g., at a point 536), typically the lead connector 532 is connected toa lead extension 522. The lead extension 522, such as a Model 7495available from Medtronic, is then connected to the INS 500.

Implantation of an INS 520 typically begins with implantation of atleast one stimulation lead 524, usually while the patient is under alocal anesthetic. The stimulation lead 524 can either be percutaneouslyor surgically implanted. Once the stimulation lead 524 has beenimplanted and positioned, the stimulation lead's 524 distal end istypically anchored into position to minimize movement of the stimulationlead 524 after implantation. The stimulation lead's 524 proximal end canbe configured to connect to a lead extension 522.

The INS 500 is programmed with a therapy and the therapy is oftenmodified to optimize the therapy for the patient (i.e., the INS may beprogrammed with a plurality of programs or therapies such that anappropriate therapy may be administered in a given situation). In theevent that the battery 502 requires recharging, an external lead (notshown) may be used to electrically couple the battery to a chargingdevice or apparatus.

A physician programmer and a patient programmer (not shown) may also beprovided to allow a physician or a patient to control the administrationof various therapies. A physician programmer, also known as a consoleprogrammer, uses telemetry to communicate with the implanted INS 500, soa clinician can program and manage a patient's therapy stored in the INS500, troubleshoot the patient's INS 500 system, and/or collect data. Anexample of a physician programmer is a Model 7432 Console Programmeravailable from Medtronic. A patient programmer also uses telemetry tocommunicate with the INS 500, so the patient can manage some aspects ofher therapy as defined by the clinician. An example of a patientprogrammer is a Model 7434 Itrel® 3 EZ Patient Programmer available fromMedtronic.

While the medical devices described herein (e.g., systems 400 and 500)are shown and described as a defibrillator and a neurologicalstimulation device, it should be appreciated that other types ofimplantable medical devices may be utilized according to other exemplaryembodiments, such as pacemakers, cardioverters, cardiac contractilitymodulators, drug administering devices, diagnostic recorders, cochlearimplants, and the like for alleviating the adverse effects of varioushealth ailments. According to still other embodiments, non-implantablemedical devices or other types of devices may utilize batteries as areshown and described in this disclosure.

It is also contemplated that the medical devices described herein may becharged or recharged when the medical device is implanted within apatient. That is, according to an exemplary embodiment, there is no needto disconnect or remove the medical device from the patient in order tocharge or recharge the medical device. For example, transcutaneousenergy transfer (TET) may be used, in which magnetic induction is usedto deliver energy from outside the body to the implanted battery,without the need to make direct physical contact to the implantedbattery, and without the need for any portion of the implant to protrudefrom the patient's skin. According to an exemplary embodiment, aconnector may be provided external to the patient's body that may beelectrically coupled to a charging device in order to charge or rechargethe battery. According to other exemplary embodiments, medical devicesmay be provided that may require removal or detachment from the patientin order to charge or recharge the battery.

It should be understood that while the present disclosure describes theuse of lithium-ion batteries with a variety of medical devices, suchbatteries may be used in a variety of other applications, includingcomputers (e.g., laptop computers), phones (e.g., cellular, mobile, orcordless phones), automobiles, and any other device or application forwhich it may be advantageous to provide power in the form of alithium-ion battery.

It is also important to note that the construction and arrangement ofthe lithium-ion battery as shown and described with respect to thevarious exemplary embodiments is illustrative only. Although only a fewembodiments of the present inventions have been described in detail inthis disclosure, those skilled in the art who review this disclosurewill readily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter recited inthe claims. Accordingly, all such modifications are intended to beincluded within the scope of the present invention as defined in theappended claims. Other substitutions, modifications, changes andomissions may be made in the design, operating conditions andarrangement of the preferred and other exemplary embodiments withoutdeparting from the scope of the present invention as expressed in theappended claims.

1. A lithium-ion battery comprising: a positive current collector; anegative current collector; an active material provided on the positivecurrent collector; an active material layer provided on the negativecurrent collector, the active material layer comprising a primary activematerial and a secondary active material, the secondary active materialexhibiting charge and discharge capacity below a corrosion potential ofthe negative current collector, wherein the secondary active materialdoes not include lithium in the as-constructed state, and a mass oflithium provided in electrical contact with a portion of the negativecurrent collector; wherein the zero voltage crossing potential of thebattery is below the corrosion potential of the negative currentcollector and above the decomposition potential of the active materiallayer provided on the positive current collector.
 2. The lithium-ionbattery of claim 1, wherein the mass of lithium provides a lithiumcapacity sufficient to at least compensate for irreversible loss ofcapacity of the battery.
 3. The lithium-ion battery of claim 2, whereinthe mass of lithium provides a lithium capacity equal to the sum of theirreversible loss of capacity of the battery and the capacity of thesecondary active material.
 4. The lithium-ion battery of claim 3,wherein the mass of lithium is provided as a lithium patch.
 5. Thelithium-ion battery of claim 3, wherein the mass of lithium is providedas powdered lithium.
 6. The lithium-ion battery of claim 1, wherein theactive material provided on the positive current collector comprisesLiCoO₂.
 7. The lithium-ion battery of claim 6, wherein the primaryactive material comprises a carbonaceous material.
 8. The lithium-ionbattery of claim 7, wherein the secondary active material comprisesV₆O₁₃.
 9. The lithium-ion battery of claim 7, wherein the secondaryactive material comprises a material selected from the group consistingof V₂O₅, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, RuO₂, and combinations thereof.10. The lithium-ion battery of claim 6, wherein the primary activematerial comprises Li₄Ti₅O₁₂.
 11. The lithium-ion battery of claim 10,wherein the secondary active material comprises V₆O₁₃.
 12. Thelithium-ion battery of claim 10, wherein the secondary active materialcomprises a material selected from the group consisting of V₂O₅, V₃O₈,MoO₃, TiS₂, WO₂, MoO₂, RuO₂, and combinations thereof.
 13. Thelithium-ion battery of claim 1, wherein the active material provided onthe positive current collector comprises a material having the formLiCo_(x)Ni_((1-x))O₂, where x is between approximately 0.05 and 0.8. 14.The lithium-ion battery of claim 13, wherein the primary active materialcomprises a carbonaceous material.
 15. The lithium-ion battery of claim14, wherein the secondary active material comprises V₆O₁₃.
 16. Thelithium-ion battery of claim 14, wherein the secondary active materialcomprises a material selected from the group consisting of V₂O₅, V₃O₈,MoO₃, TiS₂, WO₂, MoO₂, RuO₂, and combinations thereof.
 17. Thelithium-ion battery of claim 13, wherein the primary active materialcomprises a lithium titanate material.
 18. The lithium-ion battery ofclaim 17, wherein the secondary active material comprises V₆O₁₃.
 19. Thelithium-ion battery of claim 17, wherein the secondary active materialcomprises a material selected from the group consisting of V₂O₅, V₃O₈,MoO₃, TiS₂, WO₂, MoO₂, RuO₂, and combinations thereof.
 20. Thelithium-ion battery of claim 1, wherein the lithium-ion battery has acapacity between approximately 10 mAh and 1000 mAh.
 21. The lithium-ionbattery of claim 1, wherein the lithium-ion battery has a capacity ofapproximately 75 mAh.
 22. The lithium-ion battery of claim 1, whereinthe lithium-ion battery has a capacity of approximately 300 mAh.
 23. Alithium-ion battery comprising: a positive current collector; a negativecurrent collector; an active material provided on the positive currentcollector; an active material layer provided on the negative currentcollector, the active material layer comprising a primary activematerial and a secondary active material, the secondary active materialexhibiting charge and discharge capacity below a corrosion potential ofthe negative current collector, wherein the secondary active materialdoes not include lithium in the as-constructed state, and a mass oflithium provided in electrical contact with a portion of the negativecurrent collector, wherein the mass of lithium comprises at least one ofa lithium patch and powdered lithium.
 24. The lithium-ion battery ofclaim 23, wherein the mass of lithium is provided as a lithium patch.25. The lithium-ion battery of claim 23, wherein the mass of lithium isprovided as powdered lithium.
 26. The lithium-ion battery of claim 23,wherein the mass of lithium provides a lithium capacity sufficient to atleast compensate for irreversible loss of capacity of the battery. 27.The lithium-ion battery of claim 26, wherein the mass of lithiumprovides a lithium capacity equal to the sum of the irreversible loss ofcapacity of the battery and the capacity of the secondary activematerial.
 28. The lithium-ion battery of claim 23, wherein the activematerial provided on the positive current collector comprises a materialselected from the group consisting of LiCoO₂ and LiCo_(x)Ni_((1-x))O₂,where x is between approximately 0.05 and 0.8.
 29. The lithium-ionbattery of claim 23, wherein the secondary active material comprises amaterial selected from the group consisting of V₆O₁₃, V₂O₅, V₃O₈, MoO₃,TiS₂, WO₂, MoO₂, RuO₂, and combinations thereof.
 30. The lithium-ionbattery of claim 29, wherein the secondary active material comprisesV₆O₁₃.
 31. The lithium-ion battery of claim 29, wherein the primaryactive material comprises a carbonaceous material.
 32. The lithium-ionbattery of claim 29, wherein the primary active material comprises alithium titanate material.
 33. The lithium-ion battery of claim 23,wherein the lithium-ion battery has a capacity between approximately 10mAh and 1000 mAh.
 34. A lithium-ion battery comprising: a positivecurrent collector; a negative current collector; an active materialprovided on the positive current collector; an active material layerprovided on the negative current collector, the active material layercomprising a primary active material and a secondary active material,the primary active material comprising Li₄Ti₅O₁₂ and the secondaryactive material exhibiting charge and discharge capacity below acorrosion potential of the negative current collector, wherein thesecondary active material does not include lithium in the as-constructedstate, and a mass of lithium provided in electrical contact with aportion of the negative current collector.
 35. The lithium-ion batteryof claim 34, wherein the mass of lithium is provided as a lithium patch.36. The lithium-ion battery of claim 34, wherein the mass of lithium isprovided as powdered lithium.
 37. The lithium-ion battery of claim 34,wherein the secondary active material comprises a material selected fromthe group consisting of V₆O₁₃, V₂O₅, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, RuO₂,and combinations thereof.
 38. The lithium-ion battery of claim 37,wherein the secondary active material comprises V₆O₁₃.
 39. Thelithium-ion battery of claim 37, wherein the secondary active materialcomprises a material selected from the group consisting of V₂O₅, V₃O₈,MoO₃, TiS₂, WO₂, MoO₂, RuO₂, and combinations thereof.
 40. Thelithium-ion battery of claim 37, wherein the active material provided onthe positive current collector comprises LiCoO₂.
 41. The lithium-ionbattery of claim 37, wherein the active material provided on thepositive current collector comprises a material having the formLiCo_(x)Ni_((1-x))O₂, where x is between approximately 0.05 and 0.8. 42.The lithium-ion battery of claim 34, wherein the lithium-ion battery hasa capacity between approximately 10 mAh and 1000 mAh.
 43. A lithium-ionbattery comprising: a positive current collector; a negative currentcollector; an active material provided on the positive currentcollector; an active material layer provided on the negative currentcollector, the active material layer comprising a primary activematerial and a secondary active material, the primary active materialcomprising Li₄Ti₅O₁₂ and the secondary active material exhibiting chargeand discharge capacity below a corrosion potential of the negativecurrent collector, wherein the secondary active material does notinclude lithium in the as-constructed state and comprises a materialselected from the group consisting of V₆O₁₃, V₂O₅, V₃O₈, MoO₃, TiS₂,WO₂, MoO₂, RuO₂, and combinations thereof; and a mass of lithiumprovided in electrical contact with a portion of the negative currentcollector.
 44. The lithium-ion battery of claim 43, wherein the mass oflithium is provided as a lithium patch.
 45. The lithium-ion battery ofclaim 43, wherein the mass of lithium is provided as powdered lithium.46. The lithium-ion battery of claim 43, wherein the secondary activematerial comprises V₆O₁₃.
 47. The lithium-ion battery of claim 43,wherein the secondary active material comprises a material selected fromthe group consisting of V₂O₅, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, RuO₂, andcombinations thereof.
 48. The lithium-ion battery of claim 47, whereinthe active material provided on the positive current collector comprisesLiCoO₂.
 49. The lithium-ion battery of claim 47, wherein the activematerial provided on the positive current collector comprises a materialhaving the form LiCo_(x)Ni_((1-x))O₂, where x is between approximately0.05 and 0.8.
 50. The lithium-ion battery of claim 43, wherein thelithium-ion battery has a capacity between approximately 10 mAh and 1000mAh.